Submersible vessel having an irregular polygonal stabilizing pattern



Oct. 29, 1968 A WOLFF 3,407,610

IRRE AR POLYGONAL SUBMERSIBLE VESS 'mw mcv AN STABILIZ PATTER Filed M 6,1967 FIGI H02 INVENTOR 38 PAUL A. WOLFF ATTORNEYS United States Patent 3407,610 SUBMERSIBLE VESSElJ HAVING AN IRREGULAR POLYGONAL STABILIZINGPATTERN Paul A. Wolff, Oklahoma City, Okla, assignor to Kerr- McGee OilIndustries, Inc., a corporation of Delaware Filed May 26, 1967, Ser. No.641,578 7 Claims. (Cl. 61-46.5)

ABSTRACT OF THE DISCLOSURE a combination of a square stabilizing patternand a regular triangular stabilizing pattern.

This invention relates to submersible vessels for submarine operationssuch as off-shore oil well drilling operations, and more particularly tosubmersible vessels of the type disclosed in my prior United StatesPatent No. 3,246,476, granted Apr. 19, 1966.

A submersible vessel of the type to which the invention pertainscomprises a self-contained structure which is floated to a locationwhere the submarine operation is to be performed and at that location ispartially submerged below the surface of the water to the underlyingland bottom or to a depth intermediate the surface of the water and theland bottom, and maintained in the submerged position during performanceof the submarine operation. When the operation has been completed, thevessel may be refloated for movement to another location.

Submersible vessels must possess adequate stability while floating,during submergence or refioating operations, and during performance ofthe submarine operation when the vessel is submerged. My aforesaid priorpatent discloses a construction for submersible vessels which possessesthe required order of stability with a minimum use of materials.

Submersible vessels constructed in accordance with the teachings of myprior patent comprise a plurality of upstanding elongated stabilizingmembers rigidly positioned relative to a base structure. A workingplatform is supported above and in spaced relationship with the basestructure. The elognated stabilizing members are arranged at the apicesof a substantial polygon which defines a stabilizing pattern for thevessel. A feature of the invention of my prior patent is that thecross-sectional area of the elongated stabilizing members isproportioned in accordance with the stabilizing pattern to establishmoments of inertia of the water plane areas of the plurality ofelongated stabilizing members about any axis of heel of the vessel uponsubmergence of the base structure of magnitudes to maintain themetacenter of the vessel with respect to the axis of heel above thecenter of gravity of the vessel at any depth of the submergence of thebase structure throughout the maximum depth of water to which the vesselis submersible. Thus this feature achieves righting stability. Amongother embodiments of the invention, a submersible vessel having aregular polygonal stabilizing pattern in the shape of a square and asubmersible vessel having a regular polygonal stabilizing pattern in theshape of a triangle are disclosed in my'aforesaid prior patent.

Moments of inertia'for structures havingstabilizing patterns of regularpolygonal shape and having a stabilizing member of given water planearea centered at each apex of the polygon are equal provided thatsuchapices fall on circles of equal diameter and that the combined waterplane areas of the stabilizing members of the structures in each caseare equal, so that with respect to righting stability when the basestructure of the vessel is without freeboard, the same stability isobtained irrespective of the number of stabilizing members, providing atleast three stabilizing members are employed. Thus, with respect to thesquare and equilateral, triangular stabilizing patterns, if theforegoing provisions are met, vessels with the square and the triangularstabilizing patterns possess the same high order of righting stabilitywhen the base structure loses freeboard.

It has been found, unexpectedly, that a particular combination of tworegular polygonal stabilizing patterns, one in the shape of a square andthe other in the shape of a triangle, set forth in detail hereinafter,produces an overall stabilizing pattern in the shape of an irregularpolygon having five apices, i.e., an irregular pentagon which whenincorporated in a submersible vessel of the type disclosed in my priorpatent, provides the vessel with substantially the same high order ofrighting stability as is possessed by a vessel with either the square orthe triangular stabilizing pattern, so long as the combined water planeareas of the stabilizing members of the vessels with the square,triangular and irregular pentagonal stabilizing patterns, respectively,are equal. A vessel with the irregular pentagonal stabilizing pattern,however, has a higher order of stability against overturning whensubmerged to the land bottom than a vessel with either the square or theregular triangular stabilizing pattern.

The features and advantages of the present invention will becomeapparent from the following detailed description, which, when consideredin connection with the accompanying drawings, discloses a preferredembodiment of the invention for purposes of illustration only and notfor definition of the limits of the invention. For determining the scopeof the invention, reference can be made to the appended claims.

In the drawings, in which similar reference characters denote similarelements throughout the several views:

FIGURE 1 diagrammatically shows the mutual relationship of a squarepattern and an equilateral triangular pattern as combined to form thebasis of the stabilizing pattern of the present invention;

FIGURE 2 schematically shows the irregular polygonal stabilizing patternderived from the combination of FIG- URE 1 and incorporated insubmersible vessels constructed according to the present invention; and

FIGURE 3 is an isometric view of a submersible vessel embodying theprinciples of the invention.

Referring to the drawings in greater detail, and with particularreference to FIGURE 1, a stabilizing pattern 10 of substantially squareoutline, shown in broken lines, and a stabilizing pattern 12 ofsubstantially equilateral triangular outline, shown in solid lines, aredisposed in substantially concentric, coplanar relatitonship, with oneside 14 of the triangle being generally parallel to one side 16 of thesquare to thereby position the apices of the triangular pattern at thefarthest possible dis tances from the sides of the square pattern. Thesize of the square pattern 10 and the size of the triangular pattern 12are such that the apices of each fall on circles of substantially equaldiameter. This is illustrated in FIG- URE 1, in which the apices ofsquare pattern 10 and the apices of triangular pattern 12 lie on commoncircle 18. Square pattern 10 and triangular pattern 12 are concentricbecause they have a common center C, which is also the center of circle18.

Vertical elongated stabilizing members 20, 22, 24, and 26,diagrammatically shown in horizontal cross-section, are located at theapices of the square pattern 10. In a a stable vessel with a squarestabilizing pattern 10, ac cording to my prior patent, thecross-sectional area of stabilizing members located at the apices of thesquare stabilizing pattern, which is to say, the water plane area ofsuch members, would be proportioned in accordance with the distancebetween the stabilizing members measured along the sides of the squarestabilizing pattern to achieve righting stability However, sinceaccording to the present invention the two stabilizing patterns aretheoretrically considered to be acting together, the crosssectional areaof stabilizing members 20, 22, 24 and 26 can total about one-half thearea required to achieve righting stability in my prior square pattern.

The respective cross-sectional areas of the stabilizing members 20, 22,24 and 26 are substantially equal to one another, so that substantiallyequal moments of inertia of the water plane areas of the stabilizingmembers are developed about all axes of the vessel. Therefore, thecross-sectional area of each of the stabilizing members 20, 22, 24 and26 is substantially equal to onefourth of the combined crosssectionalarea of these stabilizing members. Since the combined cross-sectionalarea of stabilizing members 20, 22, 24, and 26 can in the presentinvention be about one-half that required to establish moments ofinertia of magnitudes sufficient to achieve righting stability in avessel with my square stabilizing pattern 10, the cross-sectional areaof each of the members 20, 22, 24, and 26 can be about oneeighth of thetotal cross-sectional area of the stabilizing members of a vessel havingthe square stabilizing pattern 10.

The cross-sectional area of the stabilizing members 28, 30, and 32,which are located respectively at the apices of triangular stabilizingpattern 12, would, according to my aforesaid prior patent, beproportioned in accordance with the triangular pattern 12 to achieverighting stability. According to the present invention, however, sincetwo stabilizing patterns are acting together, the cross-sectional areaof stabilizing members 28, 30 and 32 can be proportioned in accordancewith the triangular stabilizing pattern to be about one-half the arearequired to achieve righting stability in accordance with my aforesaidprior patent.

The respective cross-sectional areas of the stabilizing members 28, 30and 32 are substantially equal to one another so the cross-sectionalarea of each of them is substantially equal to one-third of theircombined crosssectional area. Since the combined cross-sectional area ofstabilizing members 28, 30 and 32 can be about onehalf that required toestablish moments of inertia of magnitudes sutficient to maintaindesired stability in a vessel with triangular stabilizing pattern 12,the cross-sectional area of each of the members 28, 30 and 32 can beabout one-sixth of the total cross-sectional area of the stabilizingmembers of a vessel having the triangular stabilizing pattern and havingstabilizing members located at the apices of the triangular pattern andproportioned in accordance with the triangular stabilizing pattern toachieve righting stability.

In accordance with the present invention, combining the stabilizingpatterns and 12, as shown in FIG- URE 1, and proportioning thestabilizing members as discussed above and combining some of them asdiscussed hereinafter, produces a configuration for a submersible vesselin which the stabilizing members establish moments of inertia of waterplane areas of magnitudes suflicient to provide the vessel withsubstantially the same order of righting stability when the basestructure loses freeboard as is possessed by a vessel with either thesquare stabilizing pattern 10 or the triangular stabilizing pattern 12and the stabilizing members proportioned in accordance with my priorpatent. However, vessels embodying the present invention possess ahigher order of stability against overturning when submerged to the landbottom.

Referring now to FIGURE 2, a stabilizing pattern 34, formed by thesubstantially concentric coplanar disposition in FIGURE 1 of squarestabilizing pattern 10 and triangular stabilizing pattern 12, is shownto have an irregular polygonal outline having five apices. Stabilizingmembers 20', 28', 22, 36 and 38 are located at the respective apices ofirregular pentagonal stabilizing pattern 34. Stabilizing members 20' and22' in this figure correspond to the members 20 and 22 in FIGURE 1.Stabilizing member 28 corresponds to member 28 in FIGURE 1. Stabilizingmember 28' is disposed midway between stabilizing members 20 and 22 interms of clockwise procession along the periphery of the stabilizingpattern 34, as a result of the concentric, coplanar disposition in FIG-URE 1 of square stabilizing pattern 10 and triangular stabilizingpattern 12.

Stabilizing member 36 is a composite of members 26 and 32 in FIGURE 1and stabilizing member 38 is a composite of members 24 and 30 ofFIGURE 1. The crosssectional area of stabilizing member 36 issubstantially equal to the sum of the cross-sectional areas ofstabilizing member 26 and stabilizing member 32 and the crosssectionalarea of stabilizing member 38 is substantially equal to the sum of thecross-sectional areas of stabilizing members 24 and 30. It will berecalled that the crossectional area of stabilizing member 26 issubstantially equal to the cross-sectional area of either stabilizingmember 20 or 22 and the same is true of stabilizing member 24.Similarly, the cross-sectional area of either of stabilizing members 32and 36 is substantially equal to the crosssectional area of stabilizingmember 28. Therefore, the cross-sectional area of each of stabilizingmembers 36 and 38 is substantially equal to the sum of thecross-sectional area of either stabilizing member 20 or 22 and thecrosssectional area of stabilizing member 28'.

The centers of stabilizing members 36, 38, 20' and 28' and 22 all fallon circle 18. The center of stabilizing member 36 is positioned oncircle 18 at a point intermediate the centers of members 26 and 32 andthe center of member 38 is located intermediate the centers of members24 and 30, the exact location of the center of each member 36 and 38being arrived at by calculating the moment of inertia of each of thesemembers as the sum of the moments of inertia of the members 26 and 32 inthe case of member 36 and the sum of the moments of inertia of themembers 24 and 30 in the case of member 38.

A submersible vessel having a stabilizing pattern 34 has substantiallythe same high order of floating stability when the base structure losesfree-board as a submersible vessel having square stabilization pattern10 or triangular stabilizing pattern 12. However, vessel having theirregular pentagonal stabilizing pattern 34 possess a higher order ofstability against overturning when submerged to the land bottom becauseof the more favorable section modulus established by stabilizing pattern34. It will be observed that this desideratum has been accomplishedwithout an increase in the maximum radial dimension of the stabilizingpattern over the radial dimensions of square and triangular patterns 10and 14. Further, the larger area of ground contact provided bystabilizing members 36 and 38 provides greater vertical stability for adrilling or other operation conducted from location 40 than is providedeither by stabilizing members 24 and 26 or by stabilizing members 30 and32.

A submersible vessel incorporating the irregular pentagonal tabilizingpattern 34 and including stabilizing mem-" bers 20, 22, 28', 36 and 38is shown in FIGURE 3. This vessel comprises a submersible base structureindicated generally at 42 and a platform supporting structure indicatedgenerally at 44. The latter may be supported on the stabilizing membersand a deck or platform 45, shown in dotted lines, and appropriateapparatus for conducting desired submarine operations may be carried bystructure 44. Base structure 42 includes five elonagted hollow members46, 48, 50, 52 and 54, respectively, joined to the bases of thestabilizing members to form an open frame structure. Base structure 42may also include a plurality of interconnected elongated hollow members56, 58, 60, 62 and 64 positioned within the open frame structure and connected to the elongated members 46, 48, 50, 52 and 54 to form a lattice.Elongated members 46, 48, 50, 52 and 54 and the internal members 56, 58,60, 62 and 64 are rigidly joined together and generally lie in a commonhorizontal plane and may be of similar cross-sectional size and shape.Auxiliary upright supporting means 66 may be used to connect platformsupporting structure 44 and base structure 42 to help support the formerabove the base structure. Platform supporting structure 44 includesmembers 68, 70, 72, and 76, to which the upper ends of the stabilizingmembers and columns 66 are connected. Additional structural members 78,80, 82, 84 86, 88 and 90 may be located within the area defined bymembers 68, 70, 72, 74 and 76 in generally coplanar relationshiptherewith to increase the rigidity of the structure and to providesupport for platform 45.

A pair of cantilever beams 94 and 96 may be provided to extend outwardlyfrom the vessel at location 40 to provide a support for drilling meanssuch as derrick 99, between stabilizing members 36 and 38. Drillingmeans 99 are shown in exploded view.

Stabilizing members 36, 38, 20', 28' and 22' function to support theplatform 45 above the base structure 42, to stabilize the vessel whenfloating when the base structure loses freeboard, to provide stabilityto the vessel during its submergence and refloatin-g operations, asmeans for controlling ballast to establish the desired bottom reaction,and also in some cases to aid in controlling submergence and refloatingof the vessel, as discussed in detail in my aforesaid Patent No.3,246,476. The lower end portions of the stabilizing members joined tothe elongated members 46, 48, 50, 52, and 54 may be considered as beingparts of base structure 42.. The base structure, that is the structureincluding members 46, 48, 50, 52, 54, 56, 58, 60, 62, 64 and the lowerend portions of the stabilizing members 20', 28', 22', 36, and 38,provides sufiicient displacement to buoyantly support the vessel whilemaintaining the base structure with freeboard when the vessel is beingfloated to a location at which submarine operations are to be conducted.The displacement of the base structure and the displacement of theplurality of upstanding elements, the latter displacement beingconstituted mainly by the displacement of the stabilizing members, aresuflicient to buoyantly support the vessel upon submergence of the basestructure throughout a depth of water corresponding to the efiectiveheight of the stabilizing members.

The stabilizing members comprise vertically disposed elongated hollowcylindrical members having their lower ends closed by end plates (notshown). Each elongated stabilizing member presents continuous externalsurfaces and is of appreciable cross-sectional area throughout itsetfective height. In the embodiment illustrated, the major portion 97 ofthe height of the stabilizing members extending upwardly from the basestructure is of substantially constant diameter to provide across-section defining a substantially uniform area throughout itsheight, which comprises the effective height of the stabilizing membersand determines the maximum depth of water in which the vessel issubmersible. The remaining portion 98 of the stabilizing membersprovides wave clearance beneath the platform 44 when the vessel issubmerged in the maximum depth of water and is of reduced crosssectionalarea to minimize wave action influence upon the vessel.

The elongated hollow members forming the base structure and thestabilizing members 36, 38, 20', 28' and 22' are preferably ofnonrectangular cross-section, such as elliptical or circularcross-section, because the vessel is subject to hydrostatic pressures.Such members are shown in the form of hollow cylindrical elements whichmay be fabricated from formed and welded steel plates. The elongatedhollow members of the base structure are provided with spaced bulkheads(not shown) to segregate the members into a plurality of water-tightballast compartments which are provided with suitable pumps, valves andconduits for controlling ballast in the compartments, as set forth in myaforesaid prior patent. The stabilizing members are also preferablyformed to provide watertight ballast compartments provided with suitablepumps and conduits for controlling ballast therein. The base structuredisplaces a volume of water in accordance with the total mass of thevessel including the weight of apparatus and supplies required for thesubmarine operation to buoyantly support the vessel with the basestructure having freeboard, when compartments of the base structure andthe stabilizing members are properly deballasted.

When it is desired to submerge the vessel, sutlicient ballast isselectively added to the compartments of the base structure to submergethe base structure below the surface of the Water. When the basestructure loses freeboard, vertical stability of the vessel and.righting stability of the vessel about any axis of heel are obtained bythe stabilizing members 36, 38, 20', 28', and 22'. Since the effectiveheight of the stabilizing members corresponds to the maximum depth ofwater in which the vessel is submersible, all phases of stability willbe maintained throughout the submergence of the base structure. As thebuoyance presented by the stabilizing members increases upon continuedsubmergence of the base structure below the surface of the water(vertical stability), it is necessary to controllably add ballastcontinuously to the compartments throughout submergence of the vessel.Upon submergence of the base structure to the land bottom, ballast isregulated to establish the desired bottom reaction and it may beconvenient to controllably add ballast to the stabilizing members forthis purpose. When it is desired to refloat the vessel, any ballastadded to the stabilizing members is removed and then ballast isselectively removed from the compartments of the base structure torender the vessel buoyant. Thereafter, the vessel may be refloated inaccordance with the rate of ballast removal from the compartments of thebase structure.

Although the present invention has been described in connection with apreferred embodiment, resort can be made to modifications of theembodiment illustrated without departing from the spirit of theinvention, as those skilled in the art will understand. Suchmodifications are considered to be within the scope of the invention asdefined by the appended claims,

What is claimed is:

1. A submersible vessel, comprising a submersiblebase structure,

a platform, and

supporting means for supporting the platform above and in spacedrelationship with the base structure, the supporting means including aplurality of upstanding elements associated with and extending upwardlyfrom the base structure,

the plurality of upstanding elements including five elongatedstabilizing members, each extending upwardly an effective height abovethe base structure, the effective height being equal to the maximumdepth to which the vessel is submersible,

each elongated stabilizing member being located at an apex of anirregular pentagon defining a stabilizing pattern having an outlineformed by substantially concentric coplanar dispositon of a stabilizingpattern of substantially square outline and a stabilizing pattern ofsubstantially equilateral triangular outline, with one side of thetriangular stabilizing pattern generally parallel to one side of thesquare stabilizing pattern, and with all the apices of the triangularstabilizing pattern and all the apices of the square stabilizing patternlocated on a common circle,

the cross-sectional area of the five stabilizing members throughout theeffective heights thereof being proportioned in accordance with thestabilizing pattern to establish moments of inertia of the water planeareas of the five stabilizing members about any axis of heel of thevessel upon submergence of the base structure of such magnitudes as tomaintain the metacenter of the vessel with respect to the axis of heelabove the center of gravity at any depth of submergence of the basestructure throughout the maximum depth to which the vessel issubmersible.

2. A submersible vessel as defined in claim 1, wherein thecross-sectional area of the five stabilizing members is substantiallyequal to about one half the sum of the cross-sectional area of thestabilizing members of a first hypothetical vessel having stabilizingmembers located at the apices of the square stabilizing pattern andproportioned in accordance with the square stabilizing pattern toestablish moments of inertia of the Water plane areas of the stabilizingmembers of the first hypothetical Vessel about any axis of heel of thefirst hypothetical vessel of such magnitudes as to maintain themetacenter of the first hypothetical vessel with respect to the axis ofheel above the center of gravity at any depth of submergence throughoutthe maximum depth to which the first hypothetical vessel is submersible,and

the cross-sectional area of the stabilizing members of a secondhypothetical vessel having stabilizing members located at the apices ofthe triangular stabilizing pattern and proportioned in accordance withthe triangular stabilizing pattern to establish moments of inertia ofthe water plane areas of the stabilizing members of the secondhypothetical vessel about any axis of heel of the second hypotheticalvessel of such magnitudes as to maintain the metacenter of the secondhypothetical vessel with respect to the axis of heel above the center ofgravity at any depth of submergence throughout the maximum depth towhich the second hypothetical vessel is submersible.

3. A submersible vessel as defined in claim 2, wherein thecross-sectional area of each of two of the five stabilizing members,throughout the effective height thereof, is about one-eighth of thetotal cross-sectional area of the stabilizing members of the firsthypothetical vessel, and

the cross-sectional area of a third stabilizing member throughout theeffective height thereof is about onesixth of the total cross-sectionalarea of the stabilizing members of the second hypothetical vessel,

4. A submersible vessel as defined in claim 3,

the cross-sectional area of each of fourth and fifth stabilizing membersbeing equal to about one-half the sum of the cross-sectional area of astabilizing member of the first hypothetical vessel and thecrosssectional area of a stabilizing member of the second hypotheticalvessel,

the center of the cross-sectional area of each of the fourth and fifthstabilizing members being positioned to establish a moment of inertia ofthe water plane area of each of the fourth and fifth stabilizing membersof a magnitude equal to about one-half the sum of the moment of inertiaof the water plane area of said stabilizing member of the firsthypothetical vessel and the moment of inertia of the water plane area ofsaid stabilizing member of the second hypothetical vessel.

5. A submersible vessel as defined in claim 1, wherein the fivestabilizing members consist of first and second stabilizing members,each having substantially the same cross-sectional area throughout itseffective height as the other,

a third stabilizing member having a cross-sectional area throughout itseffective height which is greater than the cross-sectional area of eachof the first and second stabilizing members,

the third stabilizing member being disposed between said first andsecond stabilizing members, along the periphery of the irregularpentagonal stabilizing pattern, and

fourth and fifth stabilizing members, each having a cross-sectional areathroughout its effective height which is substantially equal to the sumof the crosssectional area of one of said first and second stabilizingmembers, and the cross-sectional area of the third stabilizing member,

said fourth and fifth stabilizing members being disposed between saidfirst and second stabilizing members along the periphery of theirregular pentagonal stabilizing pattern.

6. A submersible vessel as defined in claim 5,

the third stabilizing member being substantially equidistant from saidfirst and second stabilizing members along the periphery of theirregular pentagonal stabilizing pattern,

said fourth stabilizing member being spaced from said first stabilizingmember a distance substantially equal to the distance the fifthstabilizing member is spaced from said second stabilizing member, alongthe periphery of the irregular pentagonal stabilizing pattern, and

the centers of the cross-sectional areas of said fourth and fifthstabilizing members being spaced from each other a distance along theperiphery of the irregular pentagonal stabilizing pattern which isgreater than a side of the square stabilizing pattern and less than aside of the triangular stabilizing pattern.

7. A submersible vessel as defined in claim 5, and

further comprising,

References Cited UNITED STATES PATENTS 3/1966 Storm et al. 6l-46.54/1966 Wolff 61-465 JACOB SHAPIRO, Primary Examiner.

